Actuation method
Three methods of support actuation are available:

Spring advance ¾ The cylinder plunger is extended by an internal spring, and workpiece weight compresses the spring. Spring force can be adjusted for the desired relation to the workpiece weight. When hydraulic pressure is applied, an internal sleeve grips and holds the plunger in a fixed position. These cylinders may also be capable of air advance.

Hydraulic advance ¾ Here, the plunger is normally retracted, allowing unobstructed workpiece loading. The hydraulic advance cylinder combines an external spring advance cylinder with an internal hydraulic plunger to move it into place. After the spring advance cylinder is compressed, an internal sleeve grips the cylinder to lock it in place.

Positive locking ¾ Enerpac’s unique Collet-Lok® cylinders allow work supports to remain locked in place after hydraulic pressure has been removed. As with the other two types of supports, the Collet-Lok® plunger adjusts to the contours of the workpiece during positioning. Application of hydraulic pressure to a specific port then locks the plunger in place by means of a hydraulically driven collet. After removal of hydraulic pressure, the work support remains locked in place. Unlocking is accomplished by application of hydraulic pressure to another port. Refer to Chapter 4 for more information about Collet-Lok® cylinders.

Mounting method

Single and double-acting
Four methods of cylinder mounting are used. In each case, an internal plunger thread provides for optional end effectors. Manifold mount ¾ (spring advance and hydraulic advance cylinders) This method requires no external plumbing. Its compact configuration is attractive when space is at a premium.
Threaded body ¾ (spring advance, hydraulic advance, and positive locking cylinders) This method offers the ability to adjust the cylinder height. Threaded body cylinders are externally plumbed from the side or bottom.
Lower flange ¾ (spring advance, hydraulic advance, and positive locking cylinders) Cylinders mounted by means of a lower flange can be plumbed externally or via manifold. Advantages of these cylinders are the surface mounting (vs. a hole through the fixture) and ease of assembly/disassembly.
Cartridge style ¾ This particularly compact mounting style allows close clustering of work supports and is entirely manifold-fed.